The difference between sharpshooting rifles on the one hand and hunting rifles with telescopic sight and assault rifles on the other hand consists primarily in their much wider operational range, wherefore on the telescopic rifle sight means for setting the elevation corresponding to the ballistics of the ammunition being used is required. These consist mostly of an elevation-adjusting drum, with setting marks for the respective distances engraved at their circumference.
For the sharpshooter, however, the main problem consists in establishing the distance, in order to set that value on the elevation-adjusting drum. Since the operation range for sharpshooting rifles can reach approximately 1000 m, depending on the ammunition used, the sniper is totally overburdened in variable terrain- and visibility conditions. Therefore, one has to deal with large mistakes in the distance estimates, which to leads to missed shots even with the most accurate weapons.
There have already been attempts to establish the distance with greater precision with the aid of the rifle telescope itself. Such as with telescopic rifle sights with variable enlargement, oscillating inner tubes with inversion systems and with height- and lateral adjustment screws. The distance measurement is primarily based on the fact that it is possible to evaluate quite accurately the size of the target which is known (body size, rump length, shoulder width, head size, etc) and to compare it with the marks in the sight graticule of the telescopic rifle sight. Hereby again there are two kinds of telescopes with variable enlargement, namely such with variable and such with constant sight graticule. As is the case with the former, a calculation has to be made ##EQU1## in the case of the latter, the distance can be established with the aid of an enlargement table.
However, it is evident that this is also not a viable solution for serious situations, since after the distance determination, it is first necessary to set the elevation-adjusting drum on the respective distance mark. For this, the rifle has to be removed from its shooting position in order to read the marks on the telescope and to adjust it accordingly, as far as this is altogether possible under poor visibility conditions (such as dusk, etc.). If after that the sniper seeks his target again, in most of the cases he will find that it has disappeared and he has missed a favorable opportunity.